A program of research is proposed to investigate the underlying cause of asphasic patients' inability to name objects. Previous research has indicated that there is more than one functional deficit associated with naming impairments. Some patients appear to have a disruption of the underlying semantic representation that they construct from graphic (pictorial) inputs. Other patients appear to be unable to retrieve the proper lexical form to match an intact semantic representation. A set of experiments is proposed that probes the contribution to naming abilities of semantic and lexical processing factors in relative isolation from one another, and that systematically manipulates their interaction. A combined group/case study method is proposed, in which extensive data will be obtained on the lexical and semantic abilities of a group of anomic patients. The pattern of performance obtained from these patients with naming impairments will be compared to data obtained from comparable groups of aphasic patients with no extraordinary naming deficit, neurologically intact patients, and right-hemisphere damaged non-aphasic patients. The latter group is included as part of an effort to investigate the contribution of the non-dominant hemisphere to lexical-semantic processing.